Buggy code:
public class EntryFragment extends SwipeRefreshFragment implements LoaderManager . LoaderCallbacks < Cursor > , BaseActivity . OnFullScreenListener , EntryView . EntryViewManager { private static final String STATE_BASE_URI = "STATE_BASE_URI" ; private static final String STATE_CURRENT_PAGER_POS = "STATE_CURRENT_PAGER_POS" ; private static final String STATE_ENTRIES_IDS = "STATE_ENTRIES_IDS" ; private static final String STATE_INITIAL_ENTRY_ID = "STATE_INITIAL_ENTRY_ID" ; private int mTitlePos = - 1 ; private int mDatePos ; private int mMobilizedHtmlPos ; private int mAbstractPos ; private int mLinkPos ; private int mIsFavoritePos ; private int mIsReadPos ; private int mEnclosurePos ; private int mAuthorPos ; private int mFeedNamePos ; private int mFeedUrlPos ; private int mCurrentPagerPos = - 1 ; private Uri mBaseUri ; private long mInitialEntryId = - 1 ; private long [ ] mEntriesIds ; private boolean mFavorite ; private boolean mPreferFullText = true ; private ViewPager mEntryPager ; private EntryFragment . EntryPagerAdapter mEntryPagerAdapter ; private View mCancelFullscreenBtn ; private class EntryPagerAdapter extends PagerAdapter { private final SparseArray < EntryView > mEntryViews = new SparseArray < EntryView > ( ) ; public EntryPagerAdapter ( ) { } @ Override public int getCount ( ) { } @ Override public Object instantiateItem ( ViewGroup container , int position ) { } @ Override public void destroyItem ( ViewGroup container , int position , Object object ) { } @ Override public boolean isViewFromObject ( View view , Object object ) { } public void displayEntry ( int pagerPos , Cursor newCursor , boolean forceUpdate ) { } public Cursor getCursor ( int pagerPos ) { } public void setUpdatedCursor ( int pagerPos , Cursor newCursor ) { } public void onResume ( ) { if ( ( mEntriesIds ) != null ) { EntryView view = mEntryViews . get ( mCurrentPagerPos ) ; if ( view != null ) { view . onResume ( ) ; } } } public void onPause ( ) { } } @ Override public void onCreate ( Bundle savedInstanceState ) { } @ Override public View inflateView ( LayoutInflater inflater , ViewGroup container , Bundle savedInstanceState ) { } @ Override public void onSaveInstanceState ( Bundle outState ) { } @ Override public void onAttach ( Activity activity ) { } @ Override public void onDetach ( ) { } @ Override public void onResume ( ) { super . onResume ( ) ; mEntryPagerAdapter . onResume ( ) ; <START_BUG> if ( ( ( BaseActivity ) ( getActivity ( ) ) ) . isFullScreen ( ) ) { <END_BUG> mCancelFullscreenBtn . setVisibility ( VISIBLE ) ; } else { mCancelFullscreenBtn . setVisibility ( GONE ) ; } } @ Override public void onPause ( ) { } @ Override public void onCreateOptionsMenu ( Menu menu , MenuInflater inflater ) { } @ Override public boolean onOptionsItemSelected ( MenuItem item ) { } public void setData ( Uri uri ) { } private void refreshUI ( Cursor entryCursor ) { } private void showEnclosure ( Uri uri , String enclosure , int position1 , int position2 ) { } private void setImmersiveFullScreen ( boolean fullScreen ) { } @ Override public void onClickEnclosure ( ) { } @ Override public void onStartVideoFullScreen ( ) { } @ Override public void onEndVideoFullScreen ( ) { } @ Override public FrameLayout getVideoLayout ( ) { } @ Override public Loader < Cursor > onCreateLoader ( int id , Bundle args ) { } @ Override public void onLoadFinished ( Loader < Cursor > loader , Cursor cursor ) { } @ Override public void onLoaderReset ( Loader < Cursor > loader ) { } @ Override public void onFullScreenEnabled ( boolean isImmersive , boolean isImmersiveFallback ) { } @ Override public void onFullScreenDisabled ( ) { } @ Override public void onRefresh ( ) { } }

Fix:
if ( ( ( BaseActivity ) ( getActivity ( ) ) ) . isNormalFullScreen ( ) ) {